This study systematically investigated the influence of deposition rate on the structure, broadband optical properties (1.0–13.0 μm), and stress characteristics of Germanium (Ge) films. Additionally, a method for enhancing the performance of infrared filters based on rate-modulated deposition of Ge films was proposed. The optical absorption of Ge films in the short-wave infrared (SWIR) and long-wave infrared (LWIR) bands can be effectively reduced by modulating the deposition rate. As the deposition rate increases, the Ge films maintain an amorphous structure. The optical constants of the films in the 1.0–2.5 μm and 2.5–13.0 μm bands were precisely determined using the Cody-Lorentz model and the classical Lorentz oscillator model, respectively. Notably, higher deposition rates result in a gradual increase in the refractive index. The extinction coefficient increases with the deposition rate in the SWIR region, attributed to the widening of the Urbach tail, while it decreases in the LWIR region due to the reduced absorption caused by the Ge–O stretching mode. Additionally, the films exhibit a tensile stress that decreases with increasing deposition rate. Finally, the effectiveness of the proposed fabrication method for an infrared filter with Ge films deposited at an optimized rate was demonstrated through practical examples. This work provides theoretical and technical support for the application of Ge films in high-performance infrared filters.